Field of the Invention
The present disclosure relates to an image forming apparatus.
Description of the Related Art
In an image forming apparatus such as electrophotographic type image forming apparatus, due to an environmental condition such as temperature and humidity and charged amount of toner of developer, density of an output image and a relative position of an image with respect to a sheet change. Thereby, the image forming apparatus forms a measurement image and corrects the density of the output image based on a measurement result of the measurement image by a sensor. Also, the image forming apparatus adjusts an image forming condition for adjusting the relative position of the image with respect to the sheet.
Conventionally, to prevent adhesion of scattering paper dust or toner on a detecting surface of a sensor, an image forming apparatus comprising a sensor with a shutter and that controls opening/closing operation of the shutter through an opening/closing mechanism is known (U.S. Pat. No. 6,321,044).
However, in the image forming apparatus of this type, if the toner or stain is adhered on the opening/closing mechanism of the shutter, sometimes, the shutter cannot normally be opened/closed. In this case, the sensor may receive reflection light from a rear side of the shutter at a timing when the density of the measurement image is detected. Due to this, when a sensor output value for the measurement image is wrongly detected, it is not possible to control, with high accuracy, an image forming condition of the image forming apparatus.
Thus, the present invention is directed to restrict the image forming condition from being adjusted by the measurement result of the sensor measured when the shutter is not normally opened.